When Mobil 1 Truck & SUV 5W-40 was available, I'd run it for my two or three cold weather changes and in the summer, I did run Rotella T 15W-40 until I heard really good things about Mobil 1 Delvac 1300 super, same weight as the Rotella. I've ran it ever since and will continue to until the new Mobil 1 Turbodiesel synthetic oil is available. The 1300 super is the same price as the Rotella at the Autozone where I get it. This is also one of those threads where a search would have yielded more answers and opinions than you could digest in one sitting.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo